type DownloadTask struct {
    URL     string
    Dest    string
    Parts   int
}

func (t *DownloadTask) Start() error {
    client := &http.Client{
        Transport: &http.Transport{
            DisableCompression: true,
        },
    }

    // 分块下载实现
    var wg sync.WaitGroup
    chunkSize := t.getFileSize() / int64(t.Parts)
    
    for i := 0; i < t.Parts; i++ {
        wg.Add(1)
        go func(part int) {
            defer wg.Done()
            
            req, _ := http.NewRequest("GET", t.URL, nil)
            req.Header.Set("Range", fmt.Sprintf("bytes=%d-%d", 
                int64(part)*chunkSize,
                int64(part+1)*chunkSize-1,
            ))
            
            resp, _ := client.Do(req)
            defer resp.Body.Close()
            
            // 写入文件对应区块
            file, _ := os.OpenFile(t.Dest, os.O_WRONLY|os.O_CREATE, 0666)
            file.Seek(int64(part)*chunkSize, 0)
            io.Copy(file, resp.Body)
        }(i)
    }
    
    wg.Wait()
    return nil
}